Lines - GMAT Quantitative

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$\angle 1$ and $\angle2$ are supplementary angles. Which one has the greater measure?

Statement 1: $m \angle 1 < 100$

Statement 2: $\angle2$ is an obtuse angle.

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By definition, if $\angle 1$ and $\angle2$ are supplementary angles, then $m\angle 1 + m\angle 2 = 180$ .

If Statement 1 is assumed and $m \angle 1 < 100$ , then $m\angle 2 > 80$ . This does not answer our question, since, for example, it is possible that $m \angle 1 = 91$ and $m \angle 2 = 89$ , or vice versa.

If Statement 2 is assumed, then $m\angle 2 > 90$ , and subsequently, $m \angle 1 < 90$ ; by transitivity, $m\angle 2 > m\angle 1$ .

Note: Figure NOT drawn to scale.

Refer to the above diagram.

What is the measure of $\angle FCB$ ?

Statement 1: $m \angle FBC = 43 ^{\circ }$

Statement 2: $m \angle DCG = 43 ^{\circ }$

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If we only know that $m \angle FBC = 43 ^{\circ }$ , then we cannot surmise anything from the diagram about the measure of $\angle FCB$ . But $\angle FCB$ and $\angle DCG$ are vertical angles, which must be congruent, so if we know $m \angle DCG = 43 ^{\circ }$ , then $\angle FCB= 43 ^{\circ }$ also.

What is the measure of $\angle 1$ ?

Statement 1: $\angle 1$ is complementary to an angle that measures $48 ^{\circ }$ .

Statement 2: $\angle 1$ is adjacent to an angle that measures $42 ^{\circ }$ .

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Complementary angles have degree measures that total $90 ^{\circ }$ , so the measure of an angle complementary to a $48 ^{\circ }$ angle would have measure . If Statement 1 is assumed, then $m \angle 1= 42 ^{\circ }$ .

Statement 2 gives no useful information. Adjacent angles do not have any numerical relationship; they simply share a ray and a vertex.

Find the angle made by and the -axis.

I) goes through the origin and the point .

II) makes a degree angle between itself and the -axis.

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To find the angle of the line, recall that each quadrant has 90 degrees

I) Tells us that the line has a slope of one. This means that if we make a triangle using our line, the x-axis and a line coming up from the x-axis at 90 degrees we will have a 45/45/90 triangle. Therefore, I) tells us that our angle is 45 degrees.

II) Tells us that the line makes a 45 degree angle between itself and the y-axis. Therefore:

Therfore, we could use either statement.

Note: Figure NOT drawn to scale.

Refer to the above diagram. Evaluate $m \angle 3+ m \angle 4$ .

Statement 1: $m \angle1 + m \angle 5 = $120^{\circ }$$

Statement 2: $\bigtriangleup OPQ$ is an equilateral triangle.

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Assume Statement 1 alone. $\angle 1$ and $\angle 4$ are a pair of vertical angles, as are $\angle 3$ and $\angle 5$ . Therefore,

$m \angle 4 = m \angle 1$

$m \angle 3 = m \angle 5$

By substitution,

$m \angle 3+ m \angle 4 = m \angle 1 + m \angle 5 = 120 ^{\circ}$ .

Assume Statement 2 alone. The angles of an equilateral triangle all measure , so $m \angle POQ = 60 ^{\circ }$ .

$\angle 3$ , $\angle 4$ , and $\angle POQ$ together form a straight angle, so ,

$m \angle 3 + m \angle 4 + m \angle POQ= $180^{\circ }$$

$m \angle 3 + m \angle 4 $+60^{\circ }$ = $180^{\circ }$$

$m \angle 3+ m \angle 4 = 120 ^{\circ}$

Note: Figure NOT drawn to scale.

Refer to the above diagram. What is the measure of $\angle 1$ ?

Statement 1: $\bigtriangleup OPQ$ is an equilateral triangle.

Statement 2: $m \angle 3 = $65^{\circ }$$

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$\angle 1$ , $\angle 2$ , and $\angle 3$ together form a straight angle, so their measures total ; therefore,

$m \angle 1+m \angle2+ m \angle 3 = $180^{\circ }$$

Assume Statement 1 alone. The angles of an equilateral triangle all measure , so $m \angle POQ = 60 ^{\circ }$ ; $\angle POQ$ and $\angle 2$ form a pair of vertical angles, so they are congruent, and consequently, $m \angle 2 = $60^{\circ }$$ . Therefore,

$m \angle 1+ $60^{\circ }$ + m \angle 3 = $180^{\circ }$$

$m \angle 1 + m \angle 3 = $120^{\circ }$$

But with no further information, $m \angle 1$ cannot be calculated.

Assume Statement 2 alone. It follows that

$m \angle 1+m \angle2+ $65^{\circ }$= $180^{\circ }$$

$m \angle 1+m \angle2 $=115^{\circ }$$

Again, with no further information, $m \angle 1$ cannot be calculated.

Assume both statements to be true. $m \angle 2 = $60^{\circ }$$ as a result of Statement 1, and $m \angle 3 = $65^{\circ }$$ from Statement 2, so

$m \angle $1+60^{\circ }$ + $65^{\circ }$= $180^{\circ }$$

$m \angle $1+125^{\circ }$= $180^{\circ }$$

$m \angle $1=55^{\circ }$$

Note: Figure NOT drawn to scale.

Refer to the above diagram. Evaluate $m \angle 1+ m \angle 2$ .

Statement 1: $m \angle 2+ m \angle 3 = $122^{\circ }$$

Statement 2: $m \angle 3+ m \angle 4 = $126^{\circ }$$

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Assume Statement 1 alone. $\angle 1$ , $\angle 2$ , and $\angle 3$ together form a straight angle, so their measures total ; therefore,

$m \angle 1+m \angle2+ m \angle 3 = $180^{\circ }$$

$m \angle 1+122 ^{\circ } = $180^{\circ }$$

$m \angle $1=58^{\circ }$$

However, without any further information, we cannot determine the sum of the measures of $\angle 1$ and $\angle 2$ .

Assume Statement 2 alone. $\angle 2$ , $\angle 3$ , and $\angle 4$ together form a straight angle, so their measures total ; therefore,

$m \angle2+ m \angle 3 + m \angle 4= $180^{\circ }$$

$m \angle 2+126 ^{\circ } = $180^{\circ }$$

$m \angle 2 $=54^{\circ }$$

Again, without any further information, we cannot determine the sum of the measures of $\angle 1$ and $\angle 2$ .

Assume both statements are true. Since the measures of $\angle 1$ and $\angle 2$ can be calculated from Statements 1 and 2, respectively. We can add them:

$m \angle 1+ m \angle 2 = $58^{\circ }$+ $54^{\circ }$$=112^{\circ }$$

Note: Figure NOT drawn to scale.

Refer to the above diagram. What is the measure of $\angle 1$ ?

Statement 1: $m \angle 3+ m \angle 6 = $132^{\circ }$$

Statement 2: $m \angle 1+ m \angle 4 = $140^{\circ }$$

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Assume Statement 1 alone. $\angle 3$ and $\angle 6$ are a pair of vertical angles and are therefore congruent, so the statement

$m \angle 3+ m \angle 6 = $132^{\circ }$$

can be rewritten as

$m \angle 3+ m \angle3 = $132^{\circ }$$

$2 \cdot m \angle3 = $132^{\circ }$$

$m \angle3 = $66^{\circ }$$

$\angle 1$ , $\angle 2$ , and $\angle 3$ together form a straight angle, so their measures total ; therefore,

$m \angle 1+m \angle2+ m \angle 3 = $180^{\circ }$$

$m \angle 1+m \angle2+ 66 ^{\circ } = $180^{\circ }$$

$m \angle 1+m \angle2 = $114^{\circ }$$

But without further information, the measure of $\angle 1$ cannot be calculated.

Assume Statement 2 alone. $\angle 1$ and $\angle 4$ are a pair of vertical angles and are therefore congruent, so the statement

$m \angle 1+ m \angle 4 = $140^{\circ }$$

can be rewritten as

$m \angle 1+ m \angle 1 = $140^{\circ }$$

$2 \cdot m \angle 1 = $140^{\circ }$$

$m \angle 1 = $70^{\circ }$$

Note: Figure NOT drawn to scale.

Refer to the above diagram. What is the measure of $\angle 1$ ?

Statement 1: $\angle 6$ is a $54 ^{\circ }$ angle.

Statement 2: $\angle 2 \cong \angle 3$

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Statement 1 alone gives insufficient information to find the measure of $\angle 1$ .

$\angle 6$ , $\angle 1$ , and $\angle 2$ together form a angle; therefore,

$m \angle 1+m \angle2+ m \angle 6 = $180^{\circ }$$

$m \angle 6 = $54^{\circ }$$ , so by substitution,

$m \angle 1+m \angle2+ $54^{\circ }$ = $180^{\circ }$$

$m \angle 1+m \angle2= $126^{\circ }$$

But with no further information, the measure of $\angle 1$ cannot be calculated.

Statement 2 alone gives insufficient information for a similar reason. $\angle 1$ , $\angle 2$ , and $\angle 3$ together form a angle; therefore,

$m \angle 1+m \angle2+ m \angle 3 = $180^{\circ }$$

Since $\angle 2 \cong \angle 3$ , we can rewrite this statement as

$m \angle 1+m \angle2+ m \angle 2 = $180^{\circ }$$

$m \angle 1+2 \cdot m \angle2 = $180^{\circ }$$

Again, with no further information, the measure of $\angle 1$ cannot be calculated.

Assume both statements to be true. $\angle 2$ and $\angle 6$ are a pair of vertical angles, so $\angle 2 \cong \angle 6$ , and $m \angle 2 = m \angle 6 = $54^{\circ }$$ . Since $\angle 2 \cong \angle 3$ , then $m \angle 3 = m \angle 2 = $54^{\circ }$$ . Also,

$m \angle 1+m \angle2+ m \angle 3 = $180^{\circ }$$

By substitution,

$m \angle 1+ $54^{\circ }$+ $54^{\circ }$ = $180^{\circ }$$

$m \angle $1+108^{\circ }$ = $180^{\circ }$$

$m \angle $1=72^{\circ }$$

Note: Figure NOT drawn to scale.

Refer to the above diagram. What is the measure of $\angle 1$ ?

Statement 1: $m \angle 1 = 30 ^{\circ } + 2 \cdot m \angle 2$

Statement 2: $\angle 3$ is a $130 ^{\circ }$ angle.

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Assume Statement 1 alone. Since $\angle 1$ and $\angle 2$ form a linear pair, their measures total . Therefore, this fact, along with Statement 1, form a system of linear equations, which can be solved as follows:

$m \angle 1 = 30 ^{\circ } + 2 \cdot m \angle 2$

$m \angle 1+ m \angle 2 = $180^{\circ }$$

The second equation can be rewritten as

$m \angle 2= $180^{\circ }$ - m \angle 1$

and a substitution can be made:

$m \angle 1 = 30 ^{\circ } + 2 \cdot ( $180^{\circ }$ - m \angle 1)$

$m \angle 1 = 30 ^{\circ } + $360^{\circ }$ - 2 \cdot m \angle 1$

$m \angle 1 = $390^{\circ }$ - 2 \cdot m \angle 1$

$m \angle 1 + 2 \cdot m \angle 1 = $390^{\circ }$ - 2 \cdot m \angle 1 + 2 \cdot m \angle 1$

$3 \cdot m \angle 1 = $390^{\circ }$$

$3 \cdot m \angle 1 \div 3 = $390^{\circ }$ \div 3$

$m \angle 1 = $130^{\circ }$$

Assume Statement 2 alone. $\angle 1$ and $\angle 3$ are a pair of vertical angles, which have the same measure, so $m \angle 1=m \angle 3 = $130^{\circ }$$ .

Note: You may assume that and are not parallel lines, but you may not assume that and are parallel lines unless it is specifically stated.

Refer to the above diagram. Is the sum of the measures of $\angle ADC$ and $\angle DCB$ less than, equal to, or greater than ?

Statement 1: $m \angle 1 + m \angle 6 = $181^{\circ }$$

Statement 2: $m \angle 7 + m \angle 12 = $179^{\circ }$$

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Assume Statement 1 alone. $\angle ADC$ and $\angle 1$ form a linear pair of angles, so their measures total ; the same holds for $\angle DCB$ and $\angle 6$ . Therefore,

$m \angle 1 + m \angle ADC = $180^{\circ }$$

$m \angle 6 + m \angle DBC = $180^{\circ }$$

$m \angle 1 +m \angle ADC+ m \angle 6 + m \angle DBC = $180^{\circ }$ + $180^{\circ }$$

$( m \angle ADC+ m \angle DBC) + (m \angle 1 +m \angle 6 $)=360^{\circ }$$

$( m \angle ADC+ m \angle DBC) $+181^{\circ }$$=360^{\circ }$$

$m \angle ADC+ m \angle $DBC=179^{\circ }$ < $180^{\circ }$$

Assume Statement 2 alone. $\angle 12$ and $\angle DAB$ form a linear pair of angles, so their measures total ; the same holds for $\angle 7$ and $\angle ABC$ . Therefore,

$m \angle 12 + m \angle DAB= $180^{\circ }$$

$m \angle7 + m \angle ABC= $180^{\circ }$$

$m \angle 12 +m \angle DAB + m \angle 7 + m \angle ABC= $180^{\circ }$ + $180^{\circ }$$

$( m \angle DAB+ m \angle ABC) + (m \angle 7 +m \angle 12 $)=360^{\circ }$$

$( m \angle DAB+ m \angle ABC) + $179^{\circ }$ $=360^{\circ }$$

$m \angle DAB+ m \angle ABC $=181^{\circ }$$

$\angle DAB$ , $\angle ABC$ , $\angle DCB$ , and $\angle ADC$ are the four angles of Quadrilateral , so their degree measures total 360. Therefore,

$m \angle ADC+ m \angle DCB + \left(m \angle DAB+ m \angle ABC \right) $=360^{\circ }$$

$m \angle ADC+ m \angle DCB + 181 ^{\circ } $=360^{\circ }$$

$m \angle ADC+ m \angle DCB $=179^{\circ }$< $180^{\circ }$$

Note: You may assume that and are not parallel lines, but you may not assume that and are parallel lines unless it is specifically stated.

Refer to the above diagram. Is the sum of the measures of $\angle ADC$ and $\angle DCB$ less than, equal to, or greater than ?

Statement 1: There exists a point such that lies on $\overline{ZD}$ and lies on $\overline{ZC}$ .

Statement 2: Quadrilateral is not a trapezoid.

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Assume Statement 1 alone. Since $\overline{ZD}$ exists and includes , $\overleftrightarrow{ZD}$ and $\overleftrightarrow{DA}$ are one and the same—and this is . Similarly, $\overleftrightarrow{ZC}$ is . This means that and have a point of intersection, which is . Since falls between and and falls between and , the lines intersect on the side of that includes points and . By Euclid's Fifth Postulate, the sum of the measures of $\angle ADC$ and $\angle DCB$ is less than .

Assume Statement 2 alone. Since it is given that $t \nparallel u$ , the other two sides, $\overline{AD}$ and $\overline{BC}$ are parallel if and only if Quadrilateral is a trapezoid, which it is not. Therefore, $\overline{AD}$ and $\overline{BC}$ are not parallel, and the sum of the degree measures of same-side interior angles $\angle ADC$ and $\angle DCB$ is not equal to . However, without further information, it is impossible to determine whether the sum of the measures is less than or greater than .

Note: Figure NOT drawn to scale.

Refer to the above figure. Evaluate $m \angle 1 + m \angle 2$ .

Statement 1: $\angle 4$ and $\angle 5$ are complementary.

Statement 2: $OD \cdot $\sqrt{2}$ = OE$

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Assume Statement 1 alone. $\angle 5$ and $\angle 6$ are vertical from $\angle 1$ and $\angle 2$ , respectively, so $m \angle 1 = m \angle 2$ and $m \angle 2 = m \angle 6$ . $\angle 5$ and $\angle 6$ form a complementary pair, so, by definition

$m \angle 5 + m \angle 6 = $90^{\circ}$$

and by substitution,

$m \angle 1 + m \angle 2 = $90^{\circ}$$ .

Assume Statement 2 alone. Since $\bigtriangleup ODE$ is a right triangle whose hypotenuse is $\sqrt{2}$ times as long as a leg, it follows that $\bigtriangleup ODE$ is a 45-45-90 triangle, so $m \angle DOE = $45^{\circ }$$ .

$\angle 1$ , $\angle 2$ , $\angle 3$ , and $\angle DOE$ together form a straight angle, so their degree measures total .

$m \angle 1 + m \angle 2+ m \angle 3+m \angle DOE = $180^{\circ }$$

$m \angle 1 + m \angle 2+ m \angle 3+ $45^{\circ }$ = $180^{\circ }$$

$m \angle 1 + m \angle 2+ m \angle 3 = $135^{\circ }$$

But without further information, the sum of the degree measures of only $\angle 1$ and $\angle 2$ cannot be calculated.

Note: Figure NOT drawn to scale.

Refer to the above figure. Evaluate $m \angle 3$ .

Statement 1: $\overline{BO}$ \cong $\overline{BC}$

Statement 2: $m \angle 5 = $42^{\circ }$$

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Assume Statement 1 alone. $\overline{BO}$ and $\overline{BC}$ are congruent legs of right triangle $\bigtriangleup OBC$ , so their acute angles, one of which is $\angle BOC$ , measure . $\angle BOC$ and $\angle 3$ form a pair of vertical, and consequently, congruent, angles, so $m \angle 3 = $45^{\circ }$$ .

Statement 2 alone gives insufficient information, as $\angle 3$ and $\angle 5$ has no particular relationship that would lead to an arithmetic relationship between their angle measures.

Note: Figure NOT drawn to scale.

Refer to the above figure. Evaluate $m \angle 1+ m \angle 2$ .

Statement 1: $m \angle 3 + m \angle 4 + m \angle 5 = $131^{\circ }$$

Statement 2: $m \angle 6 + m \angle 7 + m \angle 8 = $131^{\circ }$$

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Assume Statement 1 alone. $\angle 2$ , $\angle 3$ , $\angle 4$ , and $\angle 5$ together form a straight angle, so their degree measures total .

$m \angle 2 + m \angle 3+ m \angle 4+m \angle 5 = $180^{\circ }$$

$m \angle 2 + $131^{\circ }$ = $180^{\circ }$$

$m \angle 2 = $49^{\circ }$$

Without further information, no other angle measures, including that of $\angle 1$ , can be found.

Assume Statement 2 alone. $\angle 1$ , $\angle 6$ , $\angle 7$ , and $\angle 8$ together form a straight angle, so their degree measures total .

$m \angle 1 + m \angle 6+ m \angle 7+m \angle 8 = $180^{\circ }$$

$m \angle 1 + $131^{\circ }$ = $180^{\circ }$$

$m \angle 1 = $49^{\circ }$$

Without further information, no other angle measures, including that of $\angle 2$ , can be found.

However, if both statements are assumed to be true, it follows from Statements 2 and 1 respectively, as seen before, that $m \angle 1 = $49^{\circ }$$ and $m \angle 2 = $49^{\circ }$$ , so

$m \angle 1 + m \angle 2 = $49^{\circ }$+ $49^{\circ }$ = $98^{\circ }$$ .

Note: Figure NOT drawn to scale.

Refer to the above figure. Give the measure of $\angle 1$ .

Statement 1: $m \angle 2 + m \angle 3 = $91^{\circ }$$

Statement 2: $m \angle 5 + m \angle 6 = $91^{\circ }$$

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Assume both statements to be true. We show that the two statements provide insufficient information by exploring two scenarios:

Case 1: $m \angle 1 = m \angle 3 = 45 ^{\circ }, m \angle 2 = $46^{\circ }$$

$m \angle 2 + m \angle 3 = 46 ^{\circ }+ $45^{\circ }$ = $91^{\circ }$$

$\angle 5$ and $\angle 6$ are vertical from $\angle 1$ and $\angle 2$ , respectively, so $m \angle 5 = m \angle 1$ and $m \angle 6 = m \angle 2$ , and

$m \angle 5 + m \angle 6 =m \angle 1+ m \angle 2 = 45 ^{\circ }+ $46^{\circ }$ = $91^{\circ }$$

Case 2: $m \angle 1 = m \angle 3 = 46 ^{\circ }, m \angle 2 = $45^{\circ }$$

$m \angle 2 + m \angle 3 = 45 ^{\circ }+ $46^{\circ }$ = $91^{\circ }$$

$m \angle 5 + m \angle 6 =m \angle 1+ m \angle 2 = 46 ^{\circ }+ $45^{\circ }$ = $91^{\circ }$$

The conditions of both statements are met, but $\angle 1$ assumes a different value in each scenario.

Refer to the above figure. Jane chose one of the line segments shown in the above diagram but she will not reveal which one. Which one did she choose?

Statement 1: One of the endpoints of the line segment is .

Statement 2: The line segment includes .

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If we know both statements, then we know that the segment can be either $\overline{BC}$ or $\overline{BD }$ , since each has endpoint and each includes ; we can not eliminate either, however.

How many times does and intersect?

I) is a linear equation with a slope of .

II) is quadratic equation with a vertex at .

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When we have a linear equation and a quadratic equation there are only so many times they can intersect. They can intersect 0 times, once, or twice.

I) Gives us the slope of one equation.

II) Gives us the vertex of our quadratic equation.

If you draw a picture, it should be apparent that we don't have enough information to know exactly how many times they intersect. Our quadratic could be facing up or down, and our linear equation could go straight through both arms, or it could miss it entirely. Therfore, neither statement is sufficient.

Find the 4 angles created by the two intersecting lines.

Statement 1: and

Statement 2: and $y=-$\frac{1}{2}$x+4$

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Statement 1: and

The line is a horizontal line on the x-axis. The line is a vertical line graphed along the y-axis. The lines will create perpendicular angles, which are all 90 degrees.

Statement 2: and $y=-$\frac{1}{2}$x+4$

These two functions are in form, which allows us to determine the slopes of these functions. The slopes are 2 and negative half, which are both the negative reciprocal to each other. The property of negative reciprocal slopes state that these two lines are also perpendicular to each other.

Therefore:

$\textup{EACH statement ALONE is sufficient.}$

Determine the value of the four angles created by the intersecting lines.

Statement 1: Two angles are acute, and two angles are obtuse.

Statement 2: Any two non-perpendicular intersecting lines with known equations.

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Statement 1): Two angles are acute, and two angles are obtuse.

This statement is not necessarily true. Two intersecting lines may also be perpendicular to each other, which means that all four angles are 90 degrees.

There is not enough information to justify this statement.

Statement 2: Any two non-perpendicular intersecting lines with known equations.

This is a tricky statement.

When two functions meet, they must have an intersecting point $\textup{P}$ . Both functions $\textup{f1, f2}$ can be set equal to each other to determine that intersecting point.

Draw an imaginary line $\textup{f3}$ where the line is perpendicular to the first function and passes through the second function at some known arbitrary point $\textup{P2}$ . Point $\textup{P1}$ will need to be determined.

The equation of the third function can be determined since imaginary line $\textup{f3}$ intersects equation $\textup{f1}$ at $\textup{P2}$ , and $\textup{f1}$ is also perpendicular to $\textup{f3}$ . The slope of $\textup{f3}$ can be determined since it's the negative reciprocal of the slope of $\textup{f1}$ .

After the equation $\textup{f3}$ has been determined by using point $\textup{P2}$ and the slope of $\textup{f1}$ , the point $\textup{P1}$ can also be determined by setting the functions $\textup{f2 and f3}$ equal to each other.

Once the points $\textup{P, P1, and P2}$ have been determined, the distance formula may be used to determine the lengths from $\textup{P to P1}$ , $\textup{P to P2}$ , and $\textup{P1 to P2}$ .

The Law of Sines can then be used to determine the interior angles of the triangle bounded by $\textup{P, P1, and P2}$ . Knowing one angle at the intersection of $\textup{f1, f2}$ is sufficient to solve for all four angles by supplementary and opposite angle rules.

Therefore:

$\textup{Statement 2) ALONE is sufficient, but Statement 1) ALONE is not sufficient to answer the question.}$